Actually per the MAR Hedge article helpfully provided by
@Kevin Schmit he claimed all his option trades were OTC.
Again your hindsite is 20/20 here which means you're focusing on the amount of work the government would have had to do in order to catch this one criminal knowing he was a criminal
AND having the expertise to know what type of trading someone with his claimed trading strategy would do
AND doing a trade audit of his books to the level of individual transactions. Multiply that by every fund in the world. Then add up all the entities that, like Madoff, actually aren't operating as a fund. Seriously, do a spreadsheet where you determine the level of agent you'd need, the time they'd need, what kind of subpoena power they'd require and the legal time and cost involved in that, multiplied by every entity out there that could be cheating.
Much as we would like to think the government is out there with unlimited resources and should have the ability to detect any fraud the fact is that law enforcement is only ever going to be able to audit away a very small sample and will have to depend on the deterrent effect of that, which means there will always be some fraud. Should the SEC have caught a fake DTC number, again in hindsight absolutely. Is every operation that involves humans or is programmed by humans inevitably going to have fails like that, again absolutely. I would assert that the cost and civil liberties implications of setting up an organization with a near 100% catch rate of Madoff style operations far exceeds the amount Madoff stole. Just asking your to put yourself in the shoes of setting up the type of organization you envision. Heck, you might even try to get a job there doing it. I'd be the first person cheering you on when you proved me wrong.